1. Field of the Invention
The present invention relates to an inkjet printing apparatus which uses ink for printing. Particularly, it relates to a printing method of suppressing bronze phenomenon of an image in a serial inkjet printing apparatus which uses a plurality of colors of ink.
2. Description of the Related Art
In an inkjet printing apparatus which uses pigment ink or ink of low permeability into the print medium, the ink, by nature, tends to remain on the surface of the print medium and therefore a layer is formed on the print medium in the order of the printed ink. Accordingly, properties such as glossiness or bronze phenomenon which depend on surface roughness or surface material characteristics of the printed matter are affected by the characteristics of the ink last printed on the print medium. As a result, in a serial inkjet printing apparatus configured to perform multipass printing, the degree of glossiness and bronze phenomenon in an image varies depending on the printing direction in bidirectional printing, or the mask pattern to be used or print data.
Considering the above situation, Japanese Patent Publication No. 4261980, for example, discloses a printing method of controlling the amount of ink printed in a print scan that determines the dominant color (forms the topmost surface) of a serial type inkjet printing apparatus which performs multipass printing. Specifically, focusing attention on the fact that printing of cyan ink, in particular, easily affects glossiness and bronze phenomenon, a printing method is disclosed which sets the printing rate of ink other than cyan higher than the printing rate of cyan in the print scan that determines the dominant color (forms the topmost surface). Performing such a printing method allows an ink which is unlikely to affect glossiness and bronze phenomenon to be printed on the topmost surface of the image, whereby it becomes possible to suppress uneven glossiness and generation of bronze phenomenon.
In the configuration of the Japanese Patent Publication No. 4261980, however, the effect can be obtained only in a color gamut where ink which is unlikely to affect glossiness and bronze phenomenon (e.g., yellow ink) is printed simultaneously together with ink which is likely to affect glossiness and bronze phenomenon (e.g., cyan ink). Specifically, there has been a problem that it is difficult to obtain the effect in a color gamut where the printing rate of other ink is extremely low compared with cyan ink.